Troubleshooting Strategy

Article
02/20/2014

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This chapter provides a general approach to troubleshooting, describes built-in Windows 95 features for correcting problems, and includes procedures for identifying and correcting problems.

Note:

This is a general guide to troubleshooting. For more information, see the troubleshooting sections in other chapters of the Windows 95 Resource Kit.

To troubleshoot problems with Windows 95, follow these basic steps:

Analyze symptoms and factors
Check to see if the problem is a common issue
Isolate the error conditions
Consult technical support resources

Analyzing Symptoms

Start troubleshooting by analyzing symptoms to determine a strategy for resolving the problem. Under what conditions does the problem occur? Which aspects of the operating system control those conditions? Is the problem specific to a subsystem (networks, video, and so on)?

Consider the following:

Has the system or configuration ever worked? If so, what changed?
Is the error condition reproducible or random?
Is the error specific to a particular system, configuration, or application?
What specific hardware and firmware is involved?
Are any non-Windows 95 device drivers or TSRs loaded?
Does the order by which drivers or applications start up make a difference?
Does the error still occur with Safe Mode, or Safe Mode with Network Support? (These startup options are "Using Windows 95 Startup Menu Options" later in this chapter.)

Checking for Common Issues

Check to see if the problem is a common issue by reviewing online Help, the related chapters in this book, or any .TXT or .DOC files included on the Windows 95 distribution disks. For example, check SETUP.TXT and README.TXT.

For general information about the problems listed in the following table, see the related chapter in the Windows 95 Resource Kit.

Problem	Related chapter reference
Cannot install Windows 95	Chapter 6, "Setup Technical Discussion"
Computer won't start or Windows 95 won't run	Chapter 6, "Setup Technical Discussion"
Network connectivity problem	Chapter 7, "Introduction to Windows 95 Networking"
Local or network printing problem	Chapter 23, "Printing and Fonts"
Application error or general protection fault	Chapter 22, "Application Support"

The Windows 95 online Help includes troubleshooters for solving specific problems with the following components of a computer:

Printing
Running out of memory
Freeing disk space
Hardware conflicts
Running MS-DOS programs
Using the network
Using your modem
Using Dial-Up Networking
Using Direct Cable Connection
Using a portable computer card (PCMCIA)
Starting Windows 95

To get troubleshooting assistance from Windows 95 Help

From the Start button, click Help.
At the Contents tab, click Troubleshooting, and then pick a topic from the list.

Isolating and Testing the Error Condition

Eliminating variables helps determine a problem's cause. You can isolate specific causes by removing unnecessary lines in CONFIG.SYS and AUTOEXEC.BAT. Do not remove lines that are necessary to access the hard disk or to run Windows 95 Setup.

You can also isolate the cause by changing a specific value, and then testing to see if the problem has been corrected or altered. For instance, if you suspect a damaged Registry, you could restore the Registry files (SYSTEM.DAT and USER.DAT) from backup files, and then retest.

If a component fails after upgrading to a new driver, replace it with the original driver and retest. If Windows 95 startup fails while loading a real-mode device driver, or if any device driver is suspect in causing an error condition, you can test the effect of not loading a device driver. To bypass individual, real-mode device drivers, press F8 when the Starting Windows message appears and then select the Step-By-Step Confirmation option. (This process is described in detail in "Safe Mode" later in this chapter.) Removing protected-mode drivers can be done in Device Manager in the System option in Control Panel.

Test each modification individually to see if it solved the problem. Make note of all modifications and their effect on symptoms. This provides you with the information you need to contact product support personnel, if necessary, and provides an excellent reference for future troubleshooting.

Checking Technical Support Resources

When possible, post persistent problems on the appropriate online forum. Other users may have already discovered, reported, and found workarounds for your problem. Suggestions from others may save you time in tracking down the source of the problem and might give you ideas that can help.

For information about Microsoft TechNet and how to get help from product support using online resources such as The Microsoft Network, see Appendix J, "Windows 95 Resource Directory."

Windows 95 Troubleshooting Aids for Startup

Windows 95 contains log files and includes utilities that can assist you in correcting problems that occur during the setup or startup processes. In this section, the following built-in troubleshooting aids are described:

Safe Recovery with Windows 95 Setup
Installed components verification
Startup disk
Startup Menu options
WIN.COM switches

Using Safe Recovery with Windows 95 Setup

Setup uses Safe Recovery to determine what caused an installation to fail. Safe Recovery uses the information available in DETCRASH.LOG, for example, to avoid performing detection on the same device that caused Setup to fail before.

To use Safe Recovery if Setup fails

Run Setup again.
When the Safe Recovery screen appears, click Safe Recovery.

You can also use the SETUPLOG.TXT, DETLOG.TXT, and BOOTLOG.TXT files in the root directory of the boot drive to determine why Setup failed. These text files contain, respectively, the Safe Recovery and hardware detection information in a readable form, plus a log of system startup actions. SETUPLOG.TXT, for example, will show the point at which Setup failed.

To automatically scan these log files for installation or detection errors, you can use the following commands in a setup script. Create a batch file containing the following text and run it from the from the root directory of the boot drive (C:\) after an unsuccessful Setup attempt.

@echo off
echo "Entries found in Setuplog.txt" > log.txt
find /i /n "installtype" setuplog.txt >> log.txt
find /i /n "installdir" setuplog.txt >> log.txt
find /i /n "detection" setuplog.txt >> log.txt
find /i /n "runningapp" setuplog.txt >> log.txt
find /i /n "rootfilesrenamed" setuplog.txt >> log.txt
find /i /n "error" setuplog.txt >> log.txt
find /i /n "failed" setuplog.txt >> log.txt
echo "Entries found in Bootlog.txt" >> log.txt
find /i /n "fail" bootlog.txt >> log.txt
find /i /n "error" bootlog.txt >> log.txt
find /i /n "dynamic load success" bootlog.txt >> log.txt
find /i /n "initcomplete success" bootlog.txt >> log.txt
echo "Entries found in Detlog.txt" >> log.txt
find /i /n "avoidmem" detlog.txt >> log.txt
find /i /n "detected" detlog.txt >> log.txt
find /i /n "error" detlog.txt >> log.txt
cls
type log.txt |more

For more information about how Safe Recovery and hardware detection work, and about the contents of the log files, see Chapter 6, "Setup Technical Discussion."

Verifying Installed Components with Windows 95 Setup

Windows 95 provides an option for verifying installed components when Setup detects an existing Windows 95 installation. When you use the Verify option, Setup reads SETUPLOG.TXT for the installed components and reruns the Setup process to verify all system components. If Verify fails as a result of a missing or damaged file, Setup reinstalls the file. As part of this verification, Setup rebuilds VMM32.VXD and recopies any required files.

Windows 95 also provides a way in the user interface to check whether the version of DLL or support file is current. For information, see "Checking for Correct File Versions" later in this chapter.

Using a Startup Disk

You can use a Windows 95 startup disk to load the operating system and display an MS-DOS command prompt. The startup disk also contains utilities for troubleshooting a malfunctioning operating system. You can create a startup disk during Windows 95 Setup or afterward in Control Panel.

Caution: It is strongly recommended that you create a startup disk as part of Windows 95 Setup, and that you maintain an updated copy of the startup disk each time you change the system configuration after installing Windows 95.

If you did not create a startup disk during Setup, you can create one using a single floppy disk.

To create a startup disk after Windows 95 is installed

In the Add/Remove Programs option in Control Panel, click the Startup Disk tab. Then click the Create Disk button, and follow the instructions on-screen.

If the system fails to start, Windows 95 displays a Startup menu which contains troubleshooting options. You can also manually prompt Windows 95 to display the Startup menu.

To display the Windows 95 Startup menu

Restart the computer. When the Starting Windows 95 message appears, press F8.

The following table describes Startup menu options. The contents of this menu can vary, depending on the options specified in the MSDOS.SYS, and the configuration of the computer.

Startup menu option	Description
Normal	Start Windows, loading all normal startup files and Registry values.
Logged (BOOTLOG.TXT)	Runs system startup creating a startup log file. For information about using BOOTLOG.TXT, see Chapter 6, "Setup Technical Discussion."
Safe Mode	Start Windows, bypassing startup files and using only basic system drivers. You can also start this option by pressing F5 or typing win /d:m at the command prompt.
Safe Mode with Network Support	Start Windows, bypassing startup files and using only basic system drivers, including basic networking. You can also start this option by pressing F6 or typing win /d:n at the command prompt.
Step-By-Step Confirmation	Start Windows, confirming startup files line by line. You can also start this option by pressing F8 when the Startup menu is displayed. For more information, see "Step-By-Step Confirmation" later in this chapter.
Command Prompt Only1	Starts the operating system with startup files and Registry, displaying only the command prompt.
Safe Mode Command Prompt Only1	Starts the operating system in Safe Mode and displays only the command prompt, bypassing startup files. Same as pressing SHIFT+F5.
Previous version of MS-DOS	Starts the version of MS-DOS previously installed on this computer. You can also start this option by pressing F4. This option is only available if BootMulti=1 in MSDOS.SYS.2

1 When you start the computer at the command prompt, you can use switches with the win command to control Windows 95 startup for troubleshooting purposes, as described in "Using WIN.COM Switches" later in this chapter.

2 For information about the options in MSDOS.SYS, see Chapter 6, "Setup Technical Discussion."

The following sections describe when to use these Startup menu options to troubleshoot system problems.

Tip Windows 95 uses entries in the MSDOS.SYS file to control Startup menu options, automatic loading of certain drivers, and path statements for system files. If Windows 95 does not start as expected, check the entries in MSDOS.SYS.

Safe Mode

If Windows 95 fails to start normally, select Safe Mode from the Startup menu to begin troubleshooting. Windows 95 automatically initiates Safe Mode if it detects that system startup failed (for example, if a WNBOOTNG.STS signature files still exists in the Windows directory), or if the Registry is corrupted (for example, if an important key such as SYSTEM is missing), or if an application requests Safe Mode.

Safe Mode bypasses startup files, including the Registry, CONFIG.SYS, AUTOEXEC.BAT, and the [Boot] and [386Enh] sections of SYSTEM.INI, and provides you with access to the Windows 95 configuration files. You can make any necessary configuration changes, and then restart Windows 95 normally.

Use Safe Mode for system startup in situations such as the following:

If Windows 95 fails to start after the Starting Windows 95 message appears
If Windows 95 seems to stall for an extended period
If Windows 95 doesn't work correctly or has unexpected results
If you cannot print to a local printer after attempting other troubleshooting steps
If your video display doesn't work correctly
If your computer stalls repeatedly
If your computer suddenly slows down
If you need to test an intermittent error condition

When starting Windows 95 in Safe Mode, only the mouse, keyboard, and standard VGA device drivers are loaded. This makes Safe Mode useful for isolating and resolving error conditions caused by both real-mode and Windows drivers. This option is identical to typing win /d:m at the command line, as described in "Using WIN.COM Switches" later in this chapter.

The Startup menu can include three to four Safe Mode options, depending on whether the computer is compressed, or part of a network. Each Safe Mode option disables a different portion of the startup process, as shown in the following table.

Action	Safe Mode	Safe Mode, Network Support	Command Prompt Only	Safe Mode Command Prompt Only
Process CONFIG.SYS and AUTOEXEC.BAT	–	–	–	–
Load HIMEM.SYS and IFSHLP.SYS	X	X	–	–
Process Registry information	–	X	–	–
Load COMMAND.COM	–	X	X	X
Load DoubleSpace or DriveSpace if present	X	X	–	X
Run Windows 95 WIN.COM	X	X	–	–
Load all Windows drivers	–	–	–	–
Load network drivers	–	X	–	–
Run NETSTART.BAT	–	X	–	–

Safe Mode Command Prompt Only

Safe Mode Command Prompt Only loads the COMMAND.COM and DoubleSpace or DriveSpace (if present) files. It does not load HIMEM.SYS, IFSHLP.SYS, or Windows 95.

The following are examples of when to use Safe Mode Command Prompt Only:

If Windows 95 fails to start, even with the Safe Mode option
If you want to use command-line switches (such as win /d:x)
If you want to use command line tools (such as editing CONFIG.SYS)
If you want to avoid loading HIMEM.SYS or IFSHLP.SYS

Safe Mode Without Compression

This option appears on the Startup menu only if the computer has a compressed drive. This option loads COMMAND.COM, and does not load any compression drivers. The computer starts at the real-mode command prompt.

The following are examples of when to use Safe Mode Without Compression:

If the computer stops responding when accessing a compressed drive
If a Corrupt CVF error occurs during system startup
If Windows 95 fails to start, and both Safe Mode (F5) and Safe Mode Command Prompt Only (SHIFT+F5) are unsuccessful
If you want to bypass compression drivers

Safe Mode with Network Support

You can use the Safe Mode With Network Support option in networking environments where users might require network connectivity to recover from a system problem. If the operating system starts with Safe Mode but not with Safe Mode with Networking, the network configuration probably requires further adjustment.

The following are examples of when to use Safe Mode with Network Support:

When Startup stalls and Safe Mode is unsuccessful
If the computer stops responding when accessing a remote network
If you cannot print to a network printer
If the computer is running shared Windows 95 installation

This option loads the following files and drivers:

HIMEM.SYS and IFSHLP.SYS (irrespective of CONFIG.SYS settings)
DoubleSpace or DriveSpace drivers (if present)
Windows 95
Basic network drivers

It also processes Registry information and runs NETSTART.BAT (if required for real-mode networking from another vendor).

This option does not process CONFIG.SYS and AUTOEXEC.BAT, but does load COMMAND.COM. It only processes AUTOEXEC.BAT if no Windows 95 version of MSDOS.SYS is present, or if the [Paths] section in MSDOS.SYS is invalid and no valid WinDir= entry is present.

If the [Paths] section and the WinDir= variable are not defined in MSDOS.SYS when you use this option, NETSTART.BAT does not run; only AUTOEXEC.BAT runs, and Windows 95 fails to load.

You cannot use Safe Mode with Network Support when the Registry is corrupted.

Most existing real-mode networks run from the startup files, and all Safe Mode options bypass these files. The NETSTART.BAT file in the Windows directory contains commands for starting Microsoft or NetWare networks. NETSTART.BAT allows Windows 95 to start most real-mode networks on individual computers without running AUTOEXEC.BAT and CONFIG.SYS.

To troubleshoot system a problem if NETSTART.BAT doesn't start the network

When the Starting Windows 95 message appears, press F8, and then select the Step-By-Step Confirmation option. (For more information, see the following section.)
Answer Yes when prompted to process startup device drivers (CONFIG.SYS) and the startup command file (AUTOEXEC.BAT).
Answer Yes to process all network driver lines.

Step-By-Step Confirmation

Step-By-Step Confirmation allows you to specify which commands and drivers the system should process by confirming each line of the startup files.

The following are examples of when to use Step-By-Step Confirmation:

If the startup process fails during loading of the startup files
If any real-mode drivers must be loaded to run Windows 95 successfully
If you need to check for Registry failure messages
If you need to verify that the expected drivers are being loaded
If you need to temporarily disable a specific driver or set of drivers
If you need to check for errors in startup files

For information about which drivers are required for system startup, see "Checking Whether a Required Driver Is Missing" later in this chapter.

When you choose to confirm system startup line by line, the following prompts appear. You can press ENTER to confirm or ESC to skip that part of system startup.

Load DoubleSpace (or DriveSpace) driver?
Process the system Registry?
Create a startup log file (BOOTLOG.TXT)?
Process your startup device drivers (CONFIG.SYS)?

Each line from CONFIG.SYS is displayed with the [Enter=Y,Esc=N] prompt. You can press TAB when the first CONFIG.SYS prompt appears to accept all options automatically.
Process your startup command file (AUTOEXEC.BAT)?

Each line from AUTOEXEC.BAT is displayed with the [Enter=Y,Esc=N] prompt. You can press TAB when the first AUTOEXEC.BAT prompt appears to accept all options automatically.
Run WIN.COM to start Windows 95?
Load all Windows drivers?

If you press ENTER to answer Yes to each prompt, the result is the same as starting Windows 95 normally except that the logo does not appear. Answering No to "Load All Windows Drivers?" runs Windows 95 in Safe Mode.

Using WIN.COM Switches

The following switches are available to start Windows 95 from the command prompt when you need to isolate an error condition:

win [/d:[f] [m] [n] [s] [v] [x]]

The /d: switch is used for troubleshooting when Windows 95 does not start correctly. The switches in the following table can be used with the /d: switch.

Switch	Description
f	Turn off 32-bit disk access. Try this if the computer appears to have disk problems, or if Windows 95 stalls. This is equivalent to 32BitDiskAccess=FALSE in SYSTEM.INI.
m	Starts Windows 95 in Safe Mode.
n	Starts Windows 95 in Safe Mode with Networking.
s	Specifies that Windows 95 not use ROM address space between F000:0000 and 1 MB for a break point. Try this if Windows 95 stalls during system startup. This is equivalent to SystemROMBreakPoint=FALSE in SYSTEM.INI.
v	Specifies that the ROM routine should handle interrupts from the hard disk controller. Try this if Windows 95 stalls during system startup or disk operations. This is equivalent to VirtualHDIRQ=FALSE in SYSTEM.INI.
x	Excludes all of the adapter area from the memory that Windows 95 scans to find unused space. This is equivalent to EMMExclude=A000-FFFF in SYSTEM.INI.

Troubleshooting Procedures

This section provides basic instructions for troubleshooting problems that may occur when running Windows 95.

Important: Create and keep a startup disk, and verify that it works before you need it. Always make backup copies of configuration files (especially SYSTEM.DAT and USER.DAT).

A particularly good time for backing up files and updating the startup disk is after you install new devices and applications, when you have a good working configuration.

If you try to copy configuration or Registry files from within Windows 95, an error message might appear. In this case, you must remove the system and hidden attributes of the files and the copy the files while running in Safe Mode Command Prompt Only to prevent the Registry from being loaded.

Checking Specific Driver Problems

Loading a specific driver in CONFIG.SYS, AUTOEXEC.BAT, or Windows 95 Registry may cause a computer to stall. This could be due to a hardware or software (device driver or TSR) conflict.

To determine whether hardware or software is stalling the computer, try the following:

Press F8 at the Starting Windows 95 message, and select Safe Mode Command Prompt Only. If this option prevents the computer from stalling on startup, a device driver or TSR is a likely cause of the problem.

Restart the computer, and press F8 again, and then select the Step-By-Step Confirmation option to check for TSRs that are loading and may be causing the problem.
If you use disk compression and the computer still stalls after using Safe Mode Command Prompt Only to start the computer, restart the computer in Safe Mode Without Compression by pressing CTRL+F5 when the Starting Windows 95 message appears.
Check the CMOS settings in the computer's BIOS configuration menus, making sure the settings match your installed hardware.
Check the hardware installation and the manufacturer's documentation to verify that all devices are correctly installed.
Check resource settings in Device Manager for specific installed hardware to make sure no conflicts exist in the IRQ, I/O address, DMA channels, and memory addresses used. Compare your actual installation with your hardware documentation for inconsistencies in the settings used. For information, see Chapter 19, "Devices."

To check whether a specific driver is stalling the computer

Restart the computer. Press F8 when the Starting Windows 95 message appears, and then select the Logged (BOOTLOG.TXT) option. Search the BOOTLOG.TXT file for errors. For information about this file, see Chapter 6, "Setup Technical Discussion."

Checking for Correct File Versions

In Windows 95, you can view a file's properties to determine its version number and other information such as when it was created. You can use this information to determine whether a DLL or other supporting file is out of date. Notice, however, that not all DLL files display this information.

To view information about a system file

In Windows Explorer, right-click the filename, and then click Properties in the context menu.
For a supporting or executable file, click the Version tab. Use the Other Version Information list to see details about the file.

Checking for Missing System Files

A missing operating system file prevents the startup process from continuing. If you are missing only the COMMAND.COM file, you can fix this problem from the Startup menu as described in "Safe Mode Command Prompt Only" earlier in this chapter, or from a Windows 95 startup disk as described in this section.

This section also describes how to check and restore the IO.SYS and MSDOS.SYS system files. Windows 95 uses the same names for the real-mode operating system files as MS-DOS does (IO.SYS, MSDOS.SYS, and COMMAND.COM). However, to support dual-boot, the MS-DOS versions of these files are renamed with a .DOS extension when you install or start Windows 95 after having started the computer with the previous operating system.

To replace or reinstall the real-mode operating system files on drive C

Start the computer using the Windows 95 startup disk.
At the command prompt for the startup drive, type sys c: to copy IO.SYS, MSDOS.SYS, DRVSPACE.BIN, and COMMAND.COM to drive C. This rewrites the boot sector.
Remove the floppy disk, and then restart the computer.

If COMMAND.COM is missing, a message indicates this and prompts you to type the path for the file.

To restore COMMAND.COM using command-line commands

Insert the startup disk into the floppy disk drive.
At the command prompt, type the following:

attrib -r -s -h c:\command.com copy a:command.com c:

If the Windows 95 MSDOS.SYS file is missing, a blue screen presents a message: "Invalid Vxd dynamic link call from IFSMGR (03)." This is followed by an error initializing IFSMGR, and startup fails.

Errors that appear during system startup related to the Registry, XMS, and IFSMGR, are all caused by invalid syntax in the specification of the [Paths] section of MSDOS.SYS or the WinDir= entry. Setting the WinDir= value causes IO.SYS to use that value to set the following environment variables:

tmp=WinDir
temp=WinDir
path=WinDir;WinDir\command
comspec=WinDir\command.com

If no valid WinDir= entry is found in MSDOS.SYS, the path defaults to C:\WINDOWS, and COMSPEC defaults to C:\COMMAND.COM.

If IO.SYS is missing, the computer stalls before the Starting Windows 95 message appears and displays a message. The message says that the system disk is invalid and prompts you to replace it. You must use a bootable Windows 95 disk (such as the startup disk) to start the computer. You will then need to reinstall the real-mode operating system files on drive C as described in the preceding procedure.

You can also restore the COMMAND.COM in Windows 95.

To restore COMMAND.COM using Windows Explorer

Restart the computer, press F8 at the Starting Windows 95 message, and then select the Safe Mode option.
Insert the startup disk into the startup drive.
Using My Computer or Windows Explorer, find COMMAND.COM on the floppy disk drive, and then drag the file from the floppy disk to the root directory of the boot drive.

Removing Unnecessary Drivers

To determine which drivers should be removed so that they will not be loaded, first try to start the computer without these drivers before removing them from CONFIG.SYS and AUTOEXEC.BAT (and .BAT files called from the AUTOEXEC.BAT).

To determine which drivers can be removed

Restart the computer, press F8 at the Starting Windows 95 message, and then select the Step-By-Step Confirmation option. Temporarily remove specific drivers or prevent TSRs from loading to determine whether the computer can run successfully without them.

Checking Whether a Required Driver Is Missing

Some computers contain devices that require a specific driver in CONFIG.SYS to correctly complete the startup process, such as drivers used for partitioning, compression, video, hard disks, and so forth.

To check for missing drivers

Press F8 when the Starting Windows 95 message appears, and select the Step-By-Step Confirmation option.
Respond Yes to all prompts. For any error messages that appear, make note of the driver involved, its location, and the specific wording of the error message. Verify that the specified driver exists in the specified location.

Do not remove any hard disk drivers, disk partitioning drivers, or disk compression drivers when starting Windows 95 using the Step-By-Step Confirmation option or while editing startup files. The following is a partial list of drivers that should not be removed.
Drivers that Should Not Be Removed

Hard disk drivers:

ah1544.sys
aspi4dos.sys
atdosxl.sys

Partitioning drivers:

dmdrvr.bin
enhdisk.sys

Compression drivers:

dblspace.bin
devswap.com

To find out about other system drivers, see the documentation for the hardware or software installed on the system.

Checking Entries in Startup Files

The CONFIG.SYS and AUTOEXEC.BAT files contain system startup drivers, settings, and paths, and you may need to verify the accuracy of these entries. To determine which drivers to load, press F8 at the Starting Windows 95 message and select Step-By-Step Confirmation.

To check entries in CONFIG.SYS, perform the following tasks:

Verify that only necessary drivers are loading.
Check for invalid syntax.

To check entries in AUTOEXEC.BAT, perform the following tasks:

To display environment variables including COMSPEC, type set at the command prompt.
Verify that paths are valid.

Checking for Conflicts at System Startup

If a computer fails to start Windows 95, try the following tasks:

Check for upper memory area conflicts. If you suspect an upper memory conflict, use win /d:x to start Windows 95.
Check whether Safe Mode resolves the problem. To verify whether loading minimal drivers will resolve the problem, use F5 or win /d:m to start Windows 95.
Check for conflict with 32-bit disk access. If you don't want to load 32-bit disk access, use win /d:f to start Windows 95.
Check for hard disk I/O conflicts. If you want to force VirtualHDIRQ=Off, use win /d:v to start Windows 95. For more information, see "Using WIN.COM Switches" earlier in this chapter.
Check for and remove unnecessary drivers and TSRs, and retry.
Check for device conflicts by using Device Manager in the System option in Control Panel.

Check for an outdated or damaged VxD by examining the BOOTLOG.TXT and then do the following:
- If it is in the Windows SYSTEM\IOSUBSYS directory, rename it.
- If it has a .386 filename extension, examine the [386Enh] section of SYSTEM.INI and remark out its lines. When renaming VxDs, be sure to change the .VXD extension. Windows 95 loads all files that in the IOSUBSYS subdirectory that have a .VXD extensions.
- If it is in VMM32.VXD, check the Windows SYSTEM\VMM32 directory for a VMM32 file, and rename or move it.

Checking Device Configuration

Errors are sometimes caused by conflicts between devices trying to use the same system resources. Device Manager provides a central place where you can verify that devices are configured correctly and do conflict with other devices.

To check for resource conflicts among devices

In the System option in Control Panel, click the Device Manager tab.
Click the + (plus) symbol to the left of the device class, and then double-click a specific device to display its Properties dialog box.
Click the Resources tab, and check the Conflicting Device List for conflicts with another device.

Note: For network adapters, resource information is provided in the Network option in Control Panel, not in Device Manager.

Also, if you use multiple configurations, you need to first select the appropriate configuration using the list in the device's Resource properties.

Checking for Free Disk Space

Running out of space on the disk drive used for TEMP and swap files can cause a variety of operational and installation errors. If you need more disk space, see the disk space troubleshooter in online Help.

To check for free space at the command prompt, try the following:

Use the chkdskdrive command at the command prompt to display the available disk space in the Bytes Available on Disk line.
Use the dirdrive command at the command prompt to view the bytes free at the end of the DIR display.

You might want to check the swap file settings.

For more information about troubleshooting memory problems, see Chapter 17, "Performance Tuning." See also the memory troubleshooter in online Help.

To check the swap file settings

In the System option in Control Panel, click the Performance tab, and then click the Virtual Memory button.

Important: By default, Windows 95 manages the virtual memory settings. Changing these settings can adversely affect system performance. The recommended setting in this dialog box is to let Windows manage virtual memory settings.

To check for lost allocation units from a command line

Press F8 when the Starting Windows 95 message appears and select the Safe Mode Command Prompt Only option.
Run ScanDisk from the Windows COMMAND directory.

ScanDisk detects lost allocation units, and prompts you to recover them.

For information about running ScanDisk in Windows 95, see Chapter 20, "Disks and File Systems."

To check the TEMP variable

At the command prompt, type set to display the TEMP variable.
Verify that the TEMP variable points to a valid drive and directory.

Check for free disk space on the drive that contains the TEMP directory. If you are printing multiple copies of a large document, or printing large PostScript documents, increase the minimum available free disk space.

Isolating File System Errors

To determine what is causing file system errors, you generally need to isolate the specific subsystem or component involved. One place to start troubleshooting file system error conditions is through the System option in Control Panel. For information about troubleshooting the file system, see Chapter 17, "Performance Tuning."

Checking for Disk Corruption

Key operating system data structures prevent system startup if they are damaged. These structures include the master boot record, the boot sector, the file allocation table, and the core operating system files.

Caution: Back up key data files before performing any disk repair operations.

Do not run any disk utilities that are not specifically designed for Windows 95. Earlier versions of disk repair utilities may not work properly. To prevent possible data loss, use a disk utility such as ScanDisk which is specifically designed for Windows 95. For information, see Chapter 20, "Disks and File Systems."

To check for disk corruption with Safe Mode Command Prompt Only

Restart the computer, press F8 when the Starting Windows 95 message appears, and then select the Safe Mode Command Prompt Only option.
Change to the Windows COMMAND directory, and then type scandisk.

This method will also check and repair the file allocation table.

If corruption is detected, you may need to replace system files and structures.